If there is one thing you will be missing while developing your mobile web application for Webkit, it is the CSS fixed position. You cannot effectively fix an element on the iPhone, and mobile devices are no powerhouse to emulate it with javascript.

More at: http://feedproxy.google.com/~r/cssglobe/~3/BK6nkuUQgbA/the-mobile-webkit-css-fixed-position-problem